Zyprexa is a mature mass tort, as the defendant has settled approximately 31,000 individual product liability lawsuits over the drug, which was widely used in the treatment of psychiatric disorders. The federal court overseeing the multidistrict litigation over Eli Lilly and Co.’s product has made an important ruling on a Daubert challenge to a plaintiff expert in 13 cases involving 20 of the remaining claimants. In re Zyprexa Products Liability Litigation, MDL No. 1596 (E.D.N.Y. May 12, 2009).

Plaintiffs proposed to call an expert to establish the specific causal relationship between the Zyprexa taken and the onset or worsening of their diabetes. After briefing and an extensive evidentiary hearing, Senior Judge Jack B. Weinstein granted Eli Lilly’s motion to disqualify Dr. Stephen J. Hamburger, M.D. While the expert met the necessary educational and experiential qualifications warranting the admissibility of his expert opinions, the court found his testimony lacked sufficient scientific reliability.

The court noted that in longstanding and highly complex litigation (read mass tort), particular emphasis must be placed on the reliability and scientific validity of the expert’s opinions. Particularly in a mature mass tort (“advanced stage” described the court) when the issues of the benefits and risks of the drug have been a focus of the scientific community for some time, precision with respect to the relevant scientific knowledge and its application to the facts of the individual cases is expected, said the court.

The record demonstrated to the court that this expert’s opinions relied on “a subjective methodology, a fast and loose application of his scientific theories to the facts, and conclusion-driven assessments on the issues of causation in the cases on which he proposes to testify,” the order said. In particular, the court pointed to the opinion that Zyprexa supposedly has a direct adverse effect on cells essential to the body’s production of insulin, even in cases in which there was no documented weight gain. This opinion was not based on sufficient facts or data, nor was it the product of a reliable method.

In applying this theory to the facts of the cases (the “fit” required by Daubert), the expert had been, in the view of the court, “shockingly careless” about the scientific facts in these cases, including whether weight gain preceded or followed the plaintiffs’ use of Zyprexa, and whether there was any weight gain at all. When confronted with these issues, he merely “shrugged off” factual discrepancies in his analyses or shifted to new theories on the fly.

Significantly, the court correctly observed that other mass torts had been subject to a kind of junk science, and it it could not “permit a major pharmaceutical litigation to become the subject of the kind of ‘rubber-stamp’ expert opinions that have so marred mass litigations such as those involving asbestos and breast implants.”